1. Technical Field
The present invention concerns a method of erecting a tower or pylon, in particular a pylon of a wind power installation, and a pylon, as well as a wind power installation having such a pylon.
2. Description of the Related Art
In setting up the foundation for a pylon care must be taken to ensure that the top side of the foundation or at least that part of the foundation on which the pylon stands is flat and exactly horizontal so that the pylon stands precisely upright.
WO 2005/095717 discloses an annular concrete form or casing on a foundation of a pylon. The form is filled with a low-viscosity grouting material (grouting mortar) and after the grouting material has set and after removal of a form, a levelling ring or load distribution ring can be placed on the surface of the set grouting material. Then a lower pylon segment can be fixed on that load distribution ring, using anchor screws which are incorporated into the foundation and which project beyond the foundation by a predetermined amount. The low viscosity of the grouting material can ensure that it itself is exactly levelled or flattened.
WO 2005/095792 describes a method of erecting a pylon on a foundation. In that case the pylon is set up by means of anchor screws anchored in segment anchors in the foundation. The anchor screws project beyond the top side of the foundation by a predetermined amount. Firstly a levelling ring or a load distribution ring is levelled out at the top side of the foundation, aligned and fixed. In the state of the art that levelling operation is effected for example in such a way that height adjusting units such as for example height adjusting screws are placed at predetermined positions on the foundation, wherein the load distribution ring firstly rests on the height adjusting screws and the load distribution ring is then levelled off by adjustment of the screws. Then the gap between the foundation and the load distribution ring is filled and the load distribution ring is lined therebeneath over its surface. That is effected with a suitable filling material such as for example grouting mortar.
The height adjusting screws include an outer element having a female screwthread and an inner element having a male screwthread. The inner element is received with that male screwthread in the female screwthread of the outer element and is adjustable in height by being screwed in and out, with respect to the outer element. The load distribution ring can be levelled by a suitable arrangement and adjustment of the height adjusting screws. To achieve good weather resistance and a secure reliable load-carrying capacity such height adjusting screws are made from high-quality steel. Very fine height adjustment is possible by the typical configuration of the screwthread, in the form of a fine screwthread.
Height adjusting screws of that kind are admittedly relatively high in price but they can reliably carry high loads. Therefore, at least three height adjusting screws are required for levelling the load distribution ring, the screws being arranged (distributed equidistantly) over the mean radius of the load distribution ring.
DE 103 47 536 A1 discloses an arrangement for anchoring a pivoting derrick crane. A spacer element which can be squeezed together is provided in that case.
DE 698 27 290 T2 describes a device for adjusting the inclination of the surface of a construction on support legs.
WO 2008/003749 A1 discloses a height adjusting unit in the form of a height adjusting screw for aligning a lower pylon segment. At its underside the height adjusting screw has a pressure distribution element which is soft in comparison with the concrete of the foundation. As an alternative thereto a height adjusting unit is also embodied by two wedges which are displaceable into each other.